The invention relates to a reciprocating piston machine with an inlet valve on the suction side and an outlet valve on the delivery side, which valves exhibit a valve body having an elastic valve disc or valve tongue, whereby the compression chamber sealed off by the reciprocating piston or similar displacer and by the valves has a pressure relief connection between compression chamber and atmosphere.
If a reciprocating piston machine under pressure or vacuum is stopped, the entire load of the gas bears on the piston and the diaphragm. When restarting, the piston force resulting from the gas load and the piston area has to be overcome by the motor starting torque. This requires far more powerful motors than would be necessary for pure full load operation.
To keep the size of the reciprocating piston machines as small and the costs incurred by the motor as low as possible, possibilities are sought to allow escape of the pressure or vacuum left in the compression chamber when the reciprocating piston machine is stopped, for instance through a solenoid valve.
To be able to save the costs of a solenoid valve and the necessary electrical circuitry, it is already known that at that valve of the reciprocating piston machine which seals against the atmosphere, a ridge be formed in the valve seat. Such a defined leakage reduces the volumetric efficiency of the known reciprocating piston machine a little. While such a defined leakage is of no consequence in the case of compressors, in the case of vacuum pumps, however, even the slightest reflux at the valve sealing against the atmosphere can significantly reduce the final pressure of this reciprocating piston machine.